The sensitivity and specificity of commercial HIV-1 and HIV-2 antibody detection tests is difficult to measure. The sensitivity and specificity for a given test kit can vary from kit to kit and lot to lot and over time due to changes in the presence and concentration of detection antigens and the reagents used to produce the detection signal. In previous studies we have studied the markers of HIV-1 infection and the immune response for early and late antibody response (i.e. classification) to both linear and conformational epitomes of viral antigens. The markers of HIV-2 infection are less well defined due to the lack of specimens from early infection. The current study is designed to investigate whether the use of well defined antibody preparations can standardize kits by measuring test sensitivity and specificity on a kit by kit basis. Antibody preparations are being collected and analyzed by Western Blot, RIPA, synthetic peptide EIA, Recombinant EIA and all IFDA licensed kits. Also employed are Chimeric antibodies, that is a murine monoclonal antibody (Vh, VL gene) with human (Ch, Cl gene), to a gp120 epitope on ENV and two GAG epitopes, one located on p17 the other on p24. Currently, we are characterizing sera to be used in these studies.